De Qi, a Threshold of the Stimulus Intensity, Elicits the Specific Response of Acupoints and Intrinsic Change of Human Brain to Acupuncture

Figure 1

Acupoints schematic diagram. Acupuncture was performed using sterile disposable stainless steel needles at two acupuncture points on the right extremity in separate runs: ST.36 (traditionally known as the Zusanli acupoint) on the leg and LI.4 (traditionally, the Hegu acupoint) on the hand. The acupuncture point ST.36 is located in the tibialis anterior muscle, 4 fingerbreadths below the kneecap and 1 fingerbreadth lateral from the anterior crest of the tibia. The acupoint LI.4 is located in the dorsal surface of the web between the thumb and the index finger. Recording electrode and reference electrode are placed on the distal end of acupoints in the right limbs. Ground wires were placed on the dorsal surface to avoid electrical disturbance.